Given a set of atoms, I would like to find (some / the most common) molecules that include only (some/all) atoms of the set. Is there any online search engine that can do this?

E.g. Atoms={C,H} --> Molecules={CH$_4$, C$_2$H$_6$, ...}


  • I am looking for known molecules.
  • It is OK if I can only find chemical formulae, so without all possible configurations.
  • 4
    $\begingroup$ Personally, I doubt so because there are literally millions, if not billions, of compounds that contain C and H (or any combination of atoms that you specify, unless it's something esoteric like Zr, N, Se). $\endgroup$
    – orthocresol
    Feb 10 '16 at 22:20
  • 1
    $\begingroup$ Is there some database where you could enter a formula like $C_aH_bO_c$ and get molecules ( compounds) that fit (where a,b and c are given integers)? Certainly by the time that you get to 100 carbons there are more unknown possible compounds than known ones. $\endgroup$
    – MaxW
    Feb 10 '16 at 22:38
  • $\begingroup$ Pft, you can even check Wikipedia for compounds containing specific elements. $\endgroup$
    – Mithoron
    Feb 10 '16 at 23:17
  • 1
    $\begingroup$ You can search ChemSpider using a formula for one... chemspider.com/… $\endgroup$
    – MaxW
    Feb 11 '16 at 3:23
  • $\begingroup$ I'm pretty certain the question here is about searching known molecules, not theoretical ones. There are millions of connected chemical-like graphs with formula N3O4P5 yet I doubt very much that many of them correspond to stable chemical structures! $\endgroup$
    – gilleain
    Feb 11 '16 at 10:02

You can use ChemSpider's full search:


and click on the 'Elements' section. Alternatively, there is a direct link here:


This gives you two periodic tables that you can select elements from for your search. I think the upper one is 'allowed' and the lower one is 'forbidden', but I haven't tested this.

Of course, as pointed out in the comments, the set {C, H} will give you most of the database! However, for rarer elements this can be a better filter.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.